Rothamsted Research

where knowledge grows

kanyukak

Kostya Kanyuka

Role(s):
Senior Research Scientist
Plant Biology & Crop Science
Harpenden
Summary:

I lead a functional genomics component of the ‘Protecting Wheat Yield’ work package in the ‘20:20® Wheat’ Institute Strategic Programme and a number of uplift projects funded by BBSRC and Industry. Research in my group is focused on identification of genes in bread wheat, which are required for susceptibility and / or defence against important phytopathogenic fungi Zymoseptoria tritici (Zt; synonyms: Mycosphaerella graminicola and Septoria tritici) that causes Septoria tritici leaf blotch disease and Fusarium graminearum (Fg) that causes Fusarium ear blight disease. Candidate wheat genes arising either from the big datasets such as RNA-sequencing of the Zt–wheat leaf and Fg–wheat ear interactions and map-based cloning projects are subjected to functional characterisation assisted by the Virus-induced gene silencing (VIGS) reverse genetic tool. Plant viruses are also employed as vectors for in planta expression (VOX) and functional characterisation of predicted fungal secreted effector proteins (virulence factors). We are also interested in undertanding a role of small non-coding RNAs in plant-pathogen interactions.

 

Current Collaborations:

  • Jason Rudd (Rothamsted) - Functional characterisation of effectors in the wheat fungal pathogen Zymoseptoria tritici, and identification of effector targets in wheat
  • Cyrille Saintenac (INRA, Clermont-Ferrand, France) - Map-based cloning of the Stb6 resistance gene, controlling resistance to Zymoseptoria tritici in wheat
  • Peter Solomon (ANU, Acton, Australia) - Dissection of wheat - Stagonospora nodorum interactions using VIGS
  • Anna Avrova (JHI, Dundee, Scotland, UK) - Functional characterisation of effectors in the barley fungal pathogen Rhynchosporium commune (previously known as R. secalis)
  • Syngenta (Europe) - Development of a new vector for protein expression and VIGS in wheat; Small non-coding RNAs in plant-pathogen interactions.

 

Phone:
+44 (0) 1582 763 133 ext: +44 1582 938232
Location:
Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ
Past Projects
Project Leader
  • Genetics and mechanisms of resistance to diseases caused by viral and fungal pathogens in wheat, barley and related plant species
  • International workshop on virus-induced gene silencing in cereals
  • Fungal effectors as activators of novel resistances in cereals
  • IDG/Identifying cell death-inducing effectors and host targets in the interaction of wheat leaves with the fungal pathogen Zymoseptoria tritici (Mycosphaerella graminicola)
Member
  • Developing a cereal fertility pipeline(CerFip) for wheat and barley
  • Combined with S5413 The Wheat Genetic Improvement Network (WGIN3) - Improving the resilience of UK wheat yield and quality through crop genetics and targeted traits analysis
  • BBSRC Embrapa - Using HIGS and si-RNA technologies to explore and control Fusarium Head Scab disease in wheat fields
  • Combined with S5413 The Wheat Genetic Improvement Network (WGIN3) - Improving the resilience of UK wheat yield and quality through crop genetics and targeted traits analysis
  • Kettles G, Bayon C, Canning G, Rudd J, and Kanyuka K. (2016). Apoplastic recognition of multiple candidate effectors from the wheat pathogen Zymoseptoria tritici in the nonhost plant Nicotiana benthamiana. New Phytologist 213, 338-350; http://dx.doi.org/10.1111/nph.14215.
  • Yang P, Habekuß A, Hofinger BJ, Kanyuka K, Kilian B, Graner A, Ordon F, Stein N. (2016) Sequence diversification in recessive alleles of two host factor genes suggests adaptive selection for bymovirus resistance in cultivated barley from East Asia. Theoretical and Applied Genetics, http://dx.doi.org/10.1007/s00122-016-2814-z.
  • Hen-Avivi S, Savin O, Racovita RC, Lee WS, Adamski N, Malitsky S, Almekias-Siegl E, Levi M, Vautrin S, Bergès H, Friedlander G, Kartvelishvily E, Ben-Zvi G, Alkan N, Uauy C, Kanyuka K, Jetter R, Distelfeld A, and Aharoni A. (2016). A metabolic gene cluster in the wheat W1 and the barley Cer-cqu loci determines β-diketone biosynthesis and glaucousness. The Plant Cell 28, 1440-1460; http://dx.doi.org/10.1105/tpc.16.00197.
  • McGrann GRD, Andongabo A, Sjökvist E, Trivedi U, Dussart F, Kaczmarek M, Mackenzie S, Fountaine JM, Taylor JMG, Paterson LJ, Gorniak K, Burnett F, Kanyuka K, Hammond-Kosack KE, Rudd JJ, Blaxter M, and Havis ND. (2016). The genome of the emerging barley pathogen Ramularia collo-cygni. BMC Genomics 17, 584; http://dx.doi.prg/10.1186/s12864-016-2928-3.
  • Kettles GJ, and Kanyuka K. (2016). Dissecting the molecular interactions between wheat and the fungal pathogen Zymoseptoria tritici. Frontiers in Plant Science 7, 508; http://dx.doi.org/10.3389/fpls.2016.00508.
  • Lee W-S, Rudd JJ, and Kanyuka K. (2015). Virus induced gene silencing (VIGS) for functional analysis of wheat genes involved in Zymoseptoria tritici susceptibility and resistance. Fungal Genetics and Biology 79, 84-88; http://dx.doi.org/10.1016/j.fgb.2015.04.006.
  • Lee WS, Devonshire BJ, Hammond-Kosack KE, Rudd JJ, and Kanyuka K. (2015). Deregulation of plant cell death through disruption of chloroplast functionality affects asexual sporulation of Zymoseptoria tritici on wheat. Molecular Plant-Microbe Interactions 28, 590-604; http://dx.doi.org/10.1094/MPMI-10-14-0346-R.
  • Lee WS, Hammond-Kosack KE, and Kanyuka K. (2015). In planta transient expression systems for monocots. In “Recent Advances in Gene Expression and Enabling Technology in Crop Plants”, Azhakanandam K, Silverstone A, Daniell H, Davey MR, eds. Springer-Verlag - New York, pp. 391-422; http://dx.doi.org/10.1007/978-1-4939-2202-4.
  • Rudd JJ, Kanyuka K, Hassani-Pak K, Derbyshire M, Andongabo A, Devonshire J, Lysenko A, Saqi M, Powers S, Hooper J, Ambroso L, Bharti A, armer A, Hammond-Kosack KE, Dietrich RA, and Courbot M. (2015). Transcriptome and metabolite profiling the infection cycle of Zymoseptoria tritici on wheat (Triticum aestivum) reveals a biphasic interaction with plant immunity involving differential pathogen chromosomal contributions, and a variation on the hemibiotrophic lifestyle definition. Plant Physiology 167, 1158–1185; http://dx.doi.org/10.1104/pp.114.255927.
  • Lee J, Orosa B, Millyard L, Edwards M, Kanyuka K, Gatehouse A, Rudd JJ, Hammond-Kosack KE, Pain N, and Sadanandom A. (2015). Functional analysis of a wheat homeodomain protein, TaR1, reveals that host chromatin remodelling influences the dynamics of the switch to necrotrophic growth in the phytopathogenic fungus Zymoseptoria tritici. New Phytologist 206, 598-605; http://dx.doi.org/10.1111/nph.13323.
  • Chakraborty N, Sharma P, Kanyuka K, Pathak RR, Choudhury D, Hooley RA, and Raghuram N. (2015). G-protein α-subunit (GPA1) regulates stress, nitrate and phosphate response, flavonoid biosynthesis, fruit/seed development and substantially shares GCR1 regulation in A. thaliana. Plant Molecular Biology; http://dx.doi.org/10.10007/s11103-015-0374-2.
  • Chakraborty N, Sharma P, Kanyuka K, Pathak RR, Choudhury D, Hooley RA, and Raghuram N. (2015). Transcriptome analysis of Arabidopsis gcr1 mutant reveals its roles in stress, hormones, secondary metabolism and phosphate starvation. PLoS One, 10(2), e0117819. http://dx.doi.org/10.1371/journal.pone.0117819.
  • Jobsri J, Allen A, Rajagopal D, Shipton M, Kanyuka K, Lomonossoff GP, Ottensmeier C, Diebold SS, Stevenson FK, and Savelyeva N. (2015). Plant virus particles carrying tumour antigen activate TLR7 and induce high levels of protective antibody. PLoS One, 10(2): e0118096. http://dx.doi.org/10.1371/journal.pone.0118096.
  • Lee W-S, Rudd JJ, Hammond-Kosack KE, and Kanyuka K. (2014). Mycosphaerella graminicola LysM effector-mediated stealth pathogenesis subverts recognition through both CERK1 and CEBiP homologues in wheat. Molecular Plant-Microbe Interactions 27, 236–243; http://dx.doi.org/10.1094/MPMI-07-13-0201-R.
  • Perovic D, Krämer I, Habekuss A, Perner K, Pickering R, Proeseler G, Kanyuka K, and Ordon F. (2014). Genetic analyses of BaMMV/BaYMV resistance in barley accession HOR4224 result in the identification of an allele of the translation initiation factor 4e (Hv-eIF4E) exclusively effective against Barley mild mosaic virus (BaMMV). Theoretical and Applied Genetics 127, 1061-1071; http://dx.doi.org/10.1007/s00122-014-2279-x. 
  • Lee W-S, Hammond-Kosack KE, and Kanyuka K. (2012). Barley stripe mosaic virus-mediated tools for investigating gene function in cereal plants and their pathogens: Virus-induced gene silencing, Host-mediated gene silencing, and Virus-mediated overexpression of heterologous proteins. Plant Physiology 160, 582-590; http://dx.doi.org/10.1104/pp.112.203489.
  • Hofinger BJ, Russell JR, Bass C, Baldwin T, dos Reis M, Hedley PE, Li Y, Macaulay M, Waugh R, Hammond-Kosack KE, and Kanyuka K. (2011). An exceptionally high nucleotide and haplotype diversity and a signature of positive selection for the eIF4E resistance gene in barley are revealed by allele mining and phylogenetic analyses of natural populations. Molecular Ecology 20, 3653-3668; http://dx.doi.org/10.1111/j.1365-294X.2011.05201.x.
  • Kutluk Yilmaz ND, Lyons RL, Smith MJ, and Kanyuka K. (2011). Investigation of soilborne mosaic virus diseases transmitted by Polymyxa graminis in cereal production areas of the Anatolian part of Turkey. European Journal of Plant Pathology 130, 59-72; http://dx.doi.org/10.1007/s10658-010-9731-9.
  • Urban M, Motteram J, Jing H-C, Powers S, Townsend J, Devonshire J, Pearman I, Kanyuka K, Franklin J, and Hammond-Kosack K. (2011). Inactivation of plant infecting fungal and viral pathogens to achieve biological containment in drainage water using UV treatment. Journal of Applied Microbiology 110, 675–687; http://dx.doi.org/10.1111/j.1365-2672.2010.04917.x.
  • Hofinger BJ, Bass C, Baldwin T, Jing H-C, Beaudoin F, Hammond-Kosack KE, and Kanyuka K. (2010). Identification and characterization of novel natural alleles of eIF4E in barley providing broad-spectrum resistance to bymoviruses. Paper 71 in: Biology of Plant-Microbe Interactions, Volume 7. Antoun H, Avis T, Brisson L, Prevost D, Trepanier M (Eds). International Society for Molecular Plant-Microbe Interactions, St. Paul, MN, USA; http://www.ismpminet.org/bookstore/vol7.asp.
  • Hofinger BJ, Jing H-C, Hammond-Kosack KE, and Kanyuka K. (2009). High-resolution melting analysis of cDNA-derived PCR amplicons for rapid and cost-effective identification of novel alleles in barley. Theoretical and Applied Genetics 119, 851-865; http://dx.doi.org/10.1007/s00122-009-1094-2.
  • Jing H-C, Bayon C, Kanyuka K, Berry S, Wenzl P, Huttner E, Kilian A, and Hammond-Kosack KE. (2009). DArT markers: diversity analyses, genomes comparison, mapping and integration with SSR markers in Triticum monococcum. BMC Genomics 10, 458; http://dx.doi.org/10.1186/1471-2164-10-458.
  • Lyons R, Kutluk Yilmaz ND, Powers S, Hammond-Kosack KE, and Kanyuka K. (2009). Characterization of two unusual features of resistance to Soilborne cereal mosaic virus in hexaploid wheat: leakiness and gradual elimination of viral coat protein from infected root tissues. Molecular Plant-Microbe Interactions 22, 560-574; http://dx.doi.org/10.1094/MPMI-22-5-0560.
  • Perovic D, Förster J, Devaux P, Hariri D, Guilleroux M, Kanyuka K, Lyons R, Weyen J, Feuerhelm D, Kastirr U, Sourdille P, Röder M, and Ordon F. (2009). Mapping and diagnostic marker development for Soil-borne cereal mosaic virus resistance in bread wheat. Molecular Breeding 23, 641–653; http://dx.doi.org/10.1007/s11032-009-9262-2.
  • Lyons R, Hammond-Kosack KE, and Kanyuka K. (2008). Identification and characterization of a novel efficient resistance response to the furoviruses SBWMV and SBCMV in barley. Molecular Plant-Microbe Interactions 21, 1193-1204; http://dx.doi.org/10.1094/MPMI-21-9-1193.
  • Zhang Y, Wang Y, Kanyuka K, Parry MAJ, Powers SJ, and Halford NG. (2008). GCN2-dependent phosphorylation of eukaryotic translation initiation factor-2α in Arabidopsis. Journal of Experimental Botany 59, 3131-3141; http://dx.doi.org/10.1093/jxb/ern169.
  • Hammond-Kosack KE, and Kanyuka K. (2007). Resistance Genes (R Genes) in Plants. In: Encyclopedia of Life Sciences. John Wiley & Sons, Ltd: Chichester; http://dx.doi.org/10.1002/9780470015902.a0020119.
  • Jing H-C, Kornyukhin D, Kanyuka K, Orford S, Zlatska A, Mitrofanova OP, Koebner R, and Hammond-Kosack K. (2007). Identification of variation in adaptively important traits and genome wide analysis of trait-marker associations in Triticum monococcum. Journal of Experimental Botany 58, 3749-3764; http://dx.doi.org/10.1093/jxb/erm225.
  • Bass C, Hendley R, Adams MJ, Hammond-Kosack K, and Kanyuka K. (2006). The Sbm1 locus conferring resistance to Soil-borne cereal mosaic virus maps to a gene-rich region on 5DL in wheat. Genome 49, 1140-1148; http://dx.doi.org/10.1139/g06-064.
  • Cabrera Poch HL, Manzanilla Lopez RH, and Kanyuka K. (2006). Functionality of resistance gene Hero, which controls plant root-infecting potato cyst nematodes, in leaves of tomato. Plant, Cell & Environment 29, 1372-1378; http://dx.doi.org/10.1111/j.1365-3040.2006.01517.x.
  • Kanyuka K, Druka A, Caldwell DG, Tymon A, McCallum N, Waugh R, and Adams MJ. (2005). Evidence that the recessive bymovirus resistance locus rym4 in barley corresponds to the eukaryotic translation initiation factor 4E gene. Molecular Plant Pathology 6, 449-458; http://dx.doi.org/10.1111/j.1364-3703.2005.00294.x.
  • Ward E, Kanyuka K, Motteram J, Kornyukhin D, and Adams MJ. (2005). The use of conventional and quantitative real-time PCR assays for Polymyxa graminis to examine host plant resistance, inoculum levels and intraspecific variation. New Phytologist 165, 875-885; http://dx.doi.org/10.1111/j.1469-8137.2004.01291.x.
  • Jones H, and Kanyuka K. (2004). Can biotechnology and genomics offer better routes to crop protection? Outlooks on Pest Management 15, 217-221; http://dx.doi.org/10.1564/15oct09.
  • Kanyuka K, McGrann G, Alhudaib K, Hariri D, and Adams MJ. (2004). Biological and sequence analysis of a novel European isolate of Barley mild mosaic virus that overcomes the barley rym5 resistance gene. Archives of Virology 149, 1469-1480; http://dx.doi.org/10.1007/s00705-004-0318-7.
  • Kanyuka K, Lovell D, Mitrofanova OP, Hammond-Kosack K, and Adams MJ. (2004). A controlled environment test for resistance to Soil-borne cereal mosaic virus and its use to determine the mode of inheritance of the resistance in the UK wheat variety Cadenza, and to screen diverse Triticum monococcum genotypes for potential sources of improved disease resistance. Plant Pathology 53, 154-160; http://dx.doi.org/10.1111/j.0032-0862.2004.01000.x.
  • Kuehne T, Shi N, Proeseler G, Adams MJ, and Kanyuka K. (2003). The ability of a bymovirus to overcome the rym4-mediated resistance in barley correlates with a codon change in the VPg coding region on RNA1. Journal of General Virology 84, 2853-2859; http://dx.doi.org/10.1099/vir.0.19347-0.
  • Kanyuka K, Ward E, and Adams MJ. (2003). Polymyxa graminis and the cereal viruses it transmits: a research challenge. Molecular Plant Pathology 4, 393-406; http://dx.doi.org/10.1046/j.1364-3703.2003.00177.x.
  • Kanyuka K, Praekelt U, Franklin KA, Billingham OE, Hooley R, Whitelam GC, and Halliday KJ. (2003). Mutations in the huge Arabidopsis gene BIG affect a range of hormone and light responses. Plant Journal 35, 57-70.
  • Kanyuka K, Couch D, and Hooley R. (2001). A higher plant seven-transmembrane receptor that influences sensitivity to cytokinins. Current Biology 11, 535.
  • Bendahmane A, Querci M, Kanyuka K, and Baulcombe DC. (2000). Agrobacterium transient expression system as a tool for the isolation of disease resistance genes: application to the Rx2 locus in potato. Plant Journal 21, 73-81.
  • Van der Vossen EAG, Rouppe van der Voort JNAM, Kanyuka K, Bendahmane A, Sandbrink H, Baulcombe DC, Bakker J, Stiekema WJ, and Klein-Lankhorst RM. (2000). Homologues of a single resistance-gene cluster in potato confer resistance to distinct pathogens: a virus and a nematode. Plant Journal 23, 567-576.
  • Kanyuka K, Bendahmane A, Rouppe van der Voort JNAM, Van der Vossen EAG, and Baulcombe DC. (1999). Mapping of intra-locus duplications and introgressed DNA: Aids to map-based cloning of genes from complex genomes illustrated by physical analysis of the Rx locus in tetraploid potato. Theoretical and Applied Genetics 98, 679-689.
  • Bendahmane A, Kanyuka K, and Baulcombe DC. (1999). The Rx gene from potato controls separate virus resistance and cell death responses. Plant Cell 11, 781-791.
  • Rouppe van der Voort J, Kanyuka K, Van der Vossen E, Bendahmane A, Lankhorst RK, Stiekema W, Baulcombe DC, and Bakker J. (1999). New pathogen resistance gene cluster on chromosome 12 of potato: Tight physical linkage of the nematode resistance gene Gpa2 and the virus resistance gene Rx. Molecular Plant-Microbe Interactions 12, 197-206.
  • Bendahmane A, Kanyuka K, and Baulcombe DC. (1997). High resolution genetical and physical mapping of the Rx gene for extreme resistance to Potato virus X in tetraploid potato. Theoretical and Applied Genetics 95, 153-162.
  • Rouppe van der Voort J, Wolters P, Folkertsma R, Hutten R, van Zandvoort P, Vinke H, Kanyuka K, Bendahmane A, Jacobsen E, Janssen R, and Bakker J. (1997). Mapping of the nematode resistance locus Gpa2 in potato using a strategy based on comigrating AFLP markers. Theoretical and Applied Genetics 95, 874-880.
  • Kanyuka KV, Vishnichenko VK, Levay KE, Kondrikov DY, Ryabov EV, and Zavriev SK. (1992). Nucleotide sequence of Shallot virus X RNA reveals a 5'-proximal cistron closely related to those of potexviruses and unique arrangement of the 3'-proximal cistrons. Journal of General Virology 73, 2553-2560.
  • Zavriev SK, Kanyuka KV, and Levay KE. (1991). The genome organization of Potato virus M RNA. Journal of General Virology 72, 9-14.
  • Morozov SY, Kanyuka KV, Levay KE, and Zavriev SK. (1990). The putative RNA replicase of Potato virus M - obvious sequence similarity with potexviruses and tymoviruses. Virology 179, 911-914.
  • Rupasov VV, Morozov SY, Kanyuka KV, and Zavriev SK. (1989). Partial nucleotide-sequence of Potato virus M RNA shows similarities to potexviruses in gene arrangement and the encoded amino acid sequences. Journal of General Virology 70, 1861-1869.

Qualifications

1991:

PhD in Molecular Biology (Institute of Agricultural Biotechnology, Moscow, Russia)

1987:

MSc in Biochemistry (Moscow State University, Moscow, Russia)

1986:

BSc in Biochemistry (Moscow State University, Moscow, Russia)

Measures of esteem

2016

  • Board of Advisors, New Phytologist
  • Invited speaker, Turkey-United Kingdom Workshop "Wheat improvement: opportunities for collaboration": "Septoria research at Rothamsted"
  • Speaker, IS-MPMI XVII Congress, Portland, Oregon, USA: "The wheat Stb6 gene controlling a gene-for-gene resistance to Zymoseptoria tritici encodes a wall-associated kinase like protein."
  • Associate Editor, Frontiers in Plant Science

2015

  • Member, Expert Working Group on Control of wheat diseases and pests of the Wheat Initiative: http://www.wheatinitiative.org/
  • Invited speaker, N8 Septoria Workshop, Durham University, UK: "Zymoseptoria tritici-wheat interactions research at Rothamsted"
  • Speaker, SEB Prague 2015: "Identification of cell death inducing effectors in non-biotrophic cereal crop infecting fungal pathogens."
  • Invited speaker, Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel: "Functional analyses of non-biotrophic fungi-wheat interactions."
  • Speaker, Zymoseptoria tritici Meeting, AgroParisTech, Paris.: "A quest for wheat genes playing a role in interaction with Z. tritici".

2014

  • Individual Special Bonus Award: In recognition of the hard work and commitment that led to winning five new research projects
  • Invited speaker, Translational Cereal Genomics Conference, Vienna, Austria, 9-11 February 2014: "Virus-induced gene silencing as a useful tool for functional genomics in wheat."

2013

  • Team Special Bonus Award: For the organisation of an International Workshop on Cereal VIGS at Rothamsted Research
  • Invited speaker, 12th International Wheat Genetics Symposium (IWGS), Yokohama, Japan, 8-14 September 2013: "Plant defence in wheat - Mycosphaerella graminicola interaction"
  • Invited speaker, James Hutton Institute, Dundee, Scotland: "A tale of one fungal pathogen of wheat: how it evades host surveillance and then hijacks host defences."

2012

  • Team Special Bonus Award: For the licencing of a new biological containment level 3 facility at Rothamsted Research
  • Appointed Institute Biological Safety Officer
  • Principle organiser, Training school for early career European researchers (Rothamsted Research, Harpenden, UK): "Virus induced gene silencing in cereal and non-cereal plant species"

2011

  • Principle organiser, 1st International Cereal Virus-induced Gene Silencing (VIGS) Workshop at Rothamsted Research, Harpenden, UK

2009

  • Speaker, International Triticeae Mapping Initiative (ITMI) / COST Action TritiGen Joint Workshop in Clermont-Ferrand, France: "A new rapid and relatively inexpensive method for mining in plant germplasm collections for novel alleles of agronomically important genes: a case study in barley"
  • Speaker, Avalon x Cadenza Reference Population Workshop, John Innes Centre, Norwich: "Virus and Septoria resistance"

2008

  • Member, Editorial Board for Molecular Plant Pathology
  • Speaker, 7th Symposium of the International Working Group on Plant Viruses with Fungal Vectors in Quedlinburg, Germany: "Characterisation of resistance to furoviruses in wheat and barley"

2007

  • Speaker, 1st Workshop on TritiGen COST action FA0604 "Triticeae genomics for the advancement of essential European crops" in Puerto de la Cruz, Tenerife, Canary Islands, Spain: "Towards fine mapping of resistance genes to Septoria tritici leaf blotch in hexaploid and diploid wheat"

2006

  • Member, Genetics Society

2005

  • PhD Student - Rebecca Lyons: Co-supervised the project "Resistance mechanisms to Soil-borne cereal mosaic virus and Soil-borne wheat mosaic virus in wheat and barley"

2002

  • Member, British Society for Plant Pathology (BSPP)
  • PhD Student - Khalid Alhudaib: Co-supervised the project "Molecular and ultrastructural studies on Barley mild mosaic virus transmission by Polymyxa graminis"